There seems to be a fairly wide disparity of thought on changing the stock rods. Ruf has indicated that although they have not had a failure, they changed rods on their 590hp(flywheel) kits because they experienced bending. CJV indicates that this bending was occuring at 680-750rwhp. Seems like quite a wide range, especially with the improvements to traction that CJV has added. Is this due to fact that since our cars are fairly new, there might not be enough high hp examples to have had problems? Or
was RUF being overly conservative? These are the only 2 examples of that I've heard of with this issue on the 996 version cars. Seems like these engines a pretty robust if we have not heard more rod related problems so far. Remember when 540hp was really pushing it with the thought that the front diff. could not handle the add power? Many are well beyond 700hp now and 800hp is right around the corner. Is 600 or 700rwhp the point where rods need to be changed? Whats the specific criteria?

 

I would expect alot has to do with not only the rpm's you are pushing to but also when you get on it. Pushing the motor off the line or only after 3500 rpm's makes a big difference as to how much power the stock rods will tolerate. Besides, doesn't Ruf have a 100,000 mile warranty. That will definitely make a difference. My stock motor went about 7500 miles.

 

I have several pics of the balance of the engine tear down and the bent rod. I presently cannot post due to the host website being down.

 

uh uh that's not a pretty picture to see

 

Click below to see the bent 996tt rod. If you click on "my gallery" you can see additional tear down pics.

https://www.6speedonline.com/gallery...cat=500&page=1

 

Ouch Chad.. that is bent!

 

sharkster,

It just gave me an excuse to build a true 996, at the wheels of course. How many second handicap do you think we will need to give an Enzo?

 

Those pistons are works of art. Is it "excessive" torque production at lower RPM that bends the rods sideways like that?

 

ebaker,

If you like these pistons, wait until you see the Wossner pistons that we had specifically built. The liners were designed to take 962 type power. Will have pics soon.

"Excessive" torque Yes, there was a little torque involved in a 1.9 second 0-60 time. The motor currently being built will hopefully have approximately 40% more torque. Maybe a 1.4 second 0-60 time.

Our goal is to break the 0-100-0, 0-150-0 and 0-200 mph records for a street legal production car. One trick being used to help Killer Angel get there is too disassemble the tranny and differencial and have all the gears treated with a wettable solid dry film lubricant. This will drop the friction loss by approximantly 3%.

 

Hey Chad,

I showed James your picture and he said it looked identical in terms of its flaw to a car he saw at Jerry Woods'.... Too bad

 

sharkster,

There is no doubt the stock 996tt is not designed to operate in the ranges we are looking to. We just needed to satisfy ourselves as to where these ranges were.

The current motor will have the GT3R crank with the larger journals. The crank will be cross drilled, knife edged and polished. The bearings will have a wettable solid dry film coating. The case will be boat tailed and shuffle pined. A three stage GT1 oil pump will be added for insurance. In addition, the Carrillo rods were designed for the GT3R crank. We are also looking at the newer reinforced 996tt case.

The bottom end should be plenty strong.

Would you like to go for a little grudge match in early October?

 

Hi Kevin,

Good to see you over here @ 6speed. The "other" engine is coming down also. We learned a few things. The Ruf rods are not designed for where we are going now. Carrillo has specifically built a set for the new motor.

I will have a pic taken of the skirt for you. Should have it by Monday. There was no damage to the liner. The crank was scraped, but no real damage. That is where the metal in the oil filter magnet came from. I understand the piston had some damage and would not be reusable.

That rod was bent on a launch. The nitrous progressively comes on at 4400 rpm's and she was launched @ redline. We have done this before but not with the new turbo's or the bigger tires, wheels and 3.16-1 first gear.

How is your monster motor coming along? I was waiting for some info. on what you were doing for cams. I couldn't wait so I bought a set of GT3 cams. They are out for profiling now.

 

Yups... no doubt. If anyone was going to bend them it was going to be you. Kevin was/is right about the max obviously. I wonder how much GT3R cranks are going for these days... Might need one

 

sharkster,

Stronger rods need to be part of your modification when you exceed 600 rwhp. As for the crank, I would say you are safe for a bit farther unless you are consistently extending the redline beyond 7000 rpm's.